Data storage systems commonly include magnetic disks that provide persistent, non-volatile storage of data. They also commonly include a cache that provides dynamic, temporary storage of data during operation for increased performance. Data stored on a disk may be copied into the cache so that the data can be accessed much more quickly by a requestor, such as a host computer. Data being written by a requestor may also be temporarily stored in the cache before it is written to a disk for persistent storage.
In a variety of settings, it is beneficial to be able to verify in or through use of a file system that a storage data object such as a file is committed to a persistent storage device, such as a magnetic disk. Two objectives of interest are: (1) verification that an object is resident on a particular storage device (exclusive of other storage devices in a system) and (2) verification that an object is in persistent storage rather than in transient or volatile memory, such as a cache.